ST. PAUL, Minn. - Officials for the Minnesota Department of Corrections say they believe that tooth decay in inmates addicted to methamphetamine is a significant driver in the doubling of prison health care costs.

The phenomenon of "meth mouth" includes symptoms such as gum disease, broken and cracked teeth and tooth decay. The state has no hard numbers, but the increased occurrence of meth mouth in prisons is widely reported. DOC health care costs rose from $1.19 million to $2.01 million in 2004.

Dentists believe several factors contribute to meth mouth. The drug often produces anxiety levels and paranoia that can contribute to teeth grinding and gnashing. Many abusers also have a dry mouth, and the absence of saliva can exacerbate the acidic nature of methamphetamine if it is smoked or snorted.

One offshoot of methamphetamine abuse also appears to be insatiable appetite for high-caffeine, high-sugar sodas, particularly Mountain Dew. That can combine with the frenetic nature of the drug, letting users go for long periods without good hygiene.

Because of the demand for emergency and urgent care from the methamphetamine users, it can now be up to a year's wait for other inmates to get routine dental care from one of the 10 dentists across the state's prison system.

With the burgeoning use of methamphetamine, a ripple effect has flooded the state's court systems and now its prison population. A quarter of all state inmates now are drug offenders, half of them for methamphetamine convictions.